Lubricant receptacle for a coolant compressor and coolant compressor

ABSTRACT

The invention relates to a lubricant receptacle ( 1 ) for vertically conveying lubricant by means of a crankshaft ( 2 ) of a coolant compressor ( 3 ), said lubricant receptacle ( 1 ) comprising at least one rotationally symmetrical, sleeve-type receiving section ( 4 ) for receiving lubricant, wherein the longitudinal axis ( 8 ) of the receiving section ( 4 ) can be arranged coaxially with a longitudinal axis of the crankshaft ( 2 ) of the coolant compressor ( 3 ), and comprising a securing section ( 16 ) connected to the receiving section ( 4 ) in order to secure the lubricant receptacle ( 1 ) on the crankshaft ( 2 ), as well as comprising at least one end region ( 5 ) connected to the receiving section ( 4 ) which closes the the receiving section ( 4 ) apart from an inlet opening ( 6 ), wherein the inlet opening ( 6 ) permits the entry of lubricant from a lubricant sump ( 7 ) of the coolant compressor ( 3 ) into the receiving section ( 4 ) of the lubricant receptacle ( 1 ) protruding at least partially into the lubricant sump ( 7 ), wherein the inlet opening ( 6 ) is arranged in the end region ( 5 ) around the longitudinal axis ( 8 ), wherein, when viewed in the direction of the longitudinal axis, the inlet opening ( 6 ) either has a circular peripheral shape and a mid-point of the inlet opening is offset in relation to the longitudinal axis ( 8 ), or the inlet opening ( 6 ) has a non-circular peripheral shape when viewed in the direction of the longitudinal axis.

FIELD OF THE INVENTION

The present invention relates to a lubricant receptacle according to thepreamble of Claim 1.

The invention also relates to a refrigerant compressor according to thepreamble of Claim 7.

PRIOR ART

Ensuring sufficient lubrication of all moving parts is especiallyimportant for refrigerant compressors. For this purpose, it can beprovided that lubricant that collects in a lubricant sump covering thebottom area of the compressor housing is conveyed via the crankshaft inthe direction of the cylinder.

To this end, a sleeve-like lubricant receptacle is often provided, whichis rotationally fixedly connected to the crankshaft and arrangedcoaxially therewith and protrudes at one end into the lubricant sump.Lubricant that has penetrated through an inlet opening from thelubricant sump into a receiving portion of the lubricant receptacle isforced by the rotation of the lubricant receptacle—which is produced byrotation of the crankshaft—into a paraboloid shape, the paraboloidextending along the inner wall of the lubricant receptacle and the innerwall of the crankshaft.

A maximum level to which the lubricant present in the receiving portionof the lubricant receptacle can be lifted in this manner is naturallyachieved in the region of the clear internal diameter of the crankshaftand depends on the square of rotational speed of the lubricantreceptacle and the square of the clear internal radius of the crankshaftor the lubricant receptacle.

With an appropriate selection of the production parameters (for example,clear internal radius of the crankshaft, height of the outlet bores) andprocess parameters (for example, rotational speed of the crankshaft,viscosity of the lubricant), it is possible to convey the lubricant fromthe bottom of the compressor housing by means of the lubricantreceptacle via the crankshaft of the compressor to the supporting pointsof the main bearing for the crankshaft, to the crank pin, and toconnecting rod of the refrigerant compressor.

A compressor having a lubricant receptacle of this kind is known from WO2009/092147 A1, for example.

When such devices are used, however, there is typically a formation ofgas bubbles within the lubricant receptacle and/or in the region of theinlet opening and/or within the entire lubricant conveying system (i.e.in the region between the lubricant sump and the components to belubricated in which lubricant is present), which gas bubbles areresponsible for temporary cut-outs of the lubrication system. Inaddition, these bubbles can lead to fluctuations of the verticalposition of the lower apex of the paraboloid. If this apex moves downinto the region of the inlet opening, this can cause an interruption ofthe lubricant conveying system and thus the collapse of the paraboloidshape of the lubricant inside the lubricant receptacle and/or thecrankshaft.

The disruption of the lubricant conveying system can result influctuations of the oil delivery from the crank pin. In extreme case,which can be considered a cessation of the oil delivery, all movingparts run without lubrication, whereby the compressor fails within avery short time.

OBJECT OF THE INVENTION

An object of the present invention is therefore that of providing alubricant receptacle—and consequently also a lubricant compressor havinga lubricant receptacle according to the invention—wherein a lastingclosure of the inlet opening due to formation of gas bubbles in theregion of the lubricant receptacle or the inlet opening can beprevented.

It should additionally be ensured that gas bubbles, once they havearisen, break up within a very short time and thus do not lead to anylonger-term closure of the lubricant receptacle.

In addition, the lubricant receptacle according to the invention shouldbe particularly cost-effective to produce and easy to install.

PRESENTATION OF THE INVENTION

In a lubricant receptacle according to the invention for verticalconveyance of lubricant by means of a crankshaft of a refrigerantcompressor, the lubricant receptacle comprising: at least onerotationally symmetrical sleeve-like receiving portion for receivinglubricant, wherein the longitudinal axis of the receiving portion can bearranged coaxially with a longitudinal axis of the crankshaft of therefrigerant compressor; a fastening portion adjoining the receivingportion, in order to fasten the lubricant receptacle on the crankshaft;and at least one end region adjoining the receiving portion, which endregion closes off the receiving portion, apart from an inlet opening,wherein the inlet opening enables entry of lubricant from a lubricantsump into the lubricant receptacle, which protrudes at least partiallyinto the lubricant sump, wherein the inlet opening is arrangedsurrounding the longitudinal axis in the end region, this object isachieved in that the inlet opening, viewed in the direction of thelongitudinal axis, either has a circular peripheral shape and a centerpoint of the inlet opening is offset from the longitudinal axis, or inthat the inlet opening has a non-circular shape viewed in the directionof the longitudinal axis.

In concrete terms, a projection, specifically an orthogonal projectionof the end region along the longitudinal axis of the receiving portion,is to be formed asymmetrically with respect to rotation about theintersection point of the longitudinal axis of the receiving portion andthe end portion, because an asymmetric design of this kind can avoidlasting closure of the inlet opening by the formation of gas bubbles inthe region of lubricant receptacle or the inlet opening. Although it ispossible in principle that the inlet opening of the lubricant receptaclemay be closed off for a brief time by a gas bubble, the lubricantreceptacle according to the invention has the effect that, due to aninhomogeneous distribution of the centripetal forces acting on any gasbubbles that may have exited from the lubricant receptacle and areclosing the inlet opening, the bubbles are unstable and immediatelydetach from the inlet opening. In such a case, the inlet opening isagain released after a very short time, a maximum of roughly 2 seconds,so that a lasting closure can be prevented.

The invention provides that the inlet opening is arranged surroundingthe longitudinal axis in the end region. The necessary asymmetry of theorthogonal projection of the end region in relation to rotations aboutthe intersection point between the longitudinal axis of the receivingportion and the end region is achieved by non-circular formation of theperipheral shape of the inlet opening, or by correspondingly offsettinga center of a circular inlet opening from the longitudinal axis.

The end region of the lubricant receptacle can either be flat, in whichcase the periphery of the inlet opening is located in a plane; or theend region of the lubricant receptacle is formed as a curved surface, sothat the periphery of the inlet opening arranged in the end regiondescribes a three-dimensional curve. In the latter case, the inletopening has a circular or non-circular peripheral shape as viewed in thedirection of the longitudinal axis.

There are advantages in terms of production if the inlet opening has itsorigin in the rotational center of the end region of the lubricantreceptacle. The necessary shape of an inlet opening of his kindenclosing the intersection point between the longitudinal axis of thereceiving portion and the end region, which shape leads to the requiredasymmetry of said projection of the end region, can be provided in thiscase in a simple manner by further machining. Proceeding from acircular, centrally arranged bore, this can create an inlet openinghaving a peripheral shape that is capable of satisfying the requiredasymmetry condition.

In addition, an inlet opening arranged surrounding the longitudinal axisleads to an even faster detachment of a gas bubble closing the inletopening. Differently from lubricant receptacles having inlet openingsthat are arranged radially outwardly—i.e. not enclosing the longitudinalaxis—gas bubbles that have formed within the lubricant receptacleaccording to the invention can reach the inlet opening faster. This isexplained by the fact that lubricant that has penetrated through theinlet opening from the lubricant sump into the receiving portion of thelubricant receptacle is initially forced by the rotation of thelubricant receptacle—which is produced by rotation of thecrankshaft—into a paraboloid shape, the paraboloid extending along theinner wall of the lubricant receptacle. During the rotation of thelubricant receptacle in an operating state of the compressor, to thecrankshaft of which the lubricant receptacle is attached, an outgassingeffect within the lubricant receptacle leads to a change in the geometryof the paraboloid. This has the effect that an apex of the paraboloid,which apex is formed in the region of the longitudinal axis of thereceiving portion, descends further and further in the direction of theend region of the lubricant receptacle. Only when the apex of theparaboloid reaches the inlet opening can a part of the paraboloid—namelythe gas bubble—escape from the lubricant receptacle. Due to thearrangement and shape of the inlet opening according to the invention,the gas bubble detaches from the inlet opening after a very shorttime—usually after a few tenths of a second. However, if the inletopening is not formed surrounding the longitudinal axis, but rather in aradially outward peripheral region of the end region, a gas bubble canescape from the lubricant receptacle—if it all—only much later. In sucha case, there can be a collapse of the paraboloid within the lubricantreceptacle or a critical reduction in the delivery of lubricant.

In principle, inlet openings of the orthogonal projection of the endregion that are shaped and arranged in a wide variety of manners canprovide the required asymmetry in relation to rotation about theintersection point of the longitudinal axis of the receiving portionwith the end region of the lubricant receptacle, i.e. the center of theprojection. For example, the aforementioned asymmetry can be achieved byan elliptical or circular inlet opening, wherein the center of acircular inlet opening does not coincide with the intersection point ofthe longitudinal axis of the receiving portion with the end region ofthe lubricant receptacle.

A preferred embodiment of the invention therefore provides that theinlet opening has an elliptical peripheral shape as viewed in thedirection of the longitudinal axis.

Inlet openings with a substantially elliptical peripheral shape thatdoes not describe a mathematically perfect ellipse, but nevertheless hasa similar appearance, can also be advantageous.

In a preferred embodiment of the lubricant receptacle, the requiredasymmetry of the inlet opening can be achieved in a particularly simpleand cost-saving manner in that the inlet opening has the shape of anelongated hole. The center of the elongated hole can either coincidewith the intersection point of the longitudinal axis of the receivingportion with the end region of the lubricant receptacle, or can beoffset therefrom. In both cases, the required asymmetry is achievedbecause the projection of the end region along the longitudinal axis ofthe receiving portion with respect to rotation about the intersectionpoint of the longitudinal axis of the receiving portion with the endregion is asymmetrical due to the elongated hole. FIG. 2 shows alubricant receptacle according to the invention having an elongatedhole, the center of which does not coincide with said intersectionpoint.

It has been found that the implementation of the inlet opening accordingto the invention as an elongated hole is particularly advantageous withrespect to the entry of lubricant from the lubricant sump into thereceiving portion, or with respect to the avoidance of lasting closuresof the inlet opening due to gas bubbles.

In a particularly preferred embodiment variant of the lubricantreceptacle according to the invention, a fluid-dynamically optimalscooping up of lubricant from the lubricant sump into the receivingportion of the lubricant receptacle can be achieved if the longitudinalhole is delimited by semicircles at both ends and the long side of theelongated hole is greater than the radius of the semicirculardelimitations.

In order to facilitate the production of a longitudinal hole of thiskind, a particularly preferred embodiment variant of the lubricantreceptacle according to the invention provides that the length of thelong side of the elongated hole is between the value of the radius ofthe semicircular delimitations and twice said value.

Long sides refer in this regard to those sides of the slotted hole thatare straight and parallel to one another. The total length of theelongated hole is composed of the length of the long side plus the tworadii of the semicircular delimitations.

Because the size and shape of the inlet opening has an influence on theparaboloid forming in the receiving portion of the lubricant receptaclein rotation, these parameters must be selected carefully. It has provedto be particularly advantageous in another particularly preferredembodiment variant of the lubricant receptacle according to theinvention if the size of the inlet opening is between 5 and 30 percent,preferably 10 and 25 percent and especially preferably between 15 and 20percent of the clear cross-sectional area of the receiving portion.Thereby a particularly advantageous paraboloid shape can be formedwithin the receiving portion.

In order to convey the lubricant present in the receiving portion of thelubricant receptacle in the direction of the cylinder through theinterior of the crankshaft by utilizing the rotation thereof, therotational paraboloid being formed must not be disturbed on the innerlateral surfaces of the lubricant receptacle and the crankshaft ifpossible.

To achieve a transition between the receiving portion of the lubricantreceptacle and the crankshaft that is as free of interruptions aspossible, it is provided that the lubricant receptacle has a fasteningportion (16) adjoining the receiving portion, in order to mount thelubricant receptacle on the crankshaft. Alternatively or additionally,fastening of the lubricant receptacle to the rotor rotationally fixedlyconnected to the crankshaft can be achieved by means of this fasteningportion.

In a preferred embodiment of the invention, the lubricant receptaclecontains at least one lubricant driver for lubricant in order to favorthe formation of the lubricant paraboloid within the lubricantreceptacle.

The lubricant driver can be formed by a rigid structure such as atwisted sheet metal element arranged in the receiving portion.

In a refrigerant compressor comprising: a hermetically sealablecompressor housing; an electric drive unit arranged in the housinginterior of the compressor housing and comprising a rotor and a stator;a crankshaft rotationally fixedly connected to the rotor; and apiston-cylinder unit arranged in the housing interior and comprising apiston movably mounted in a cylinder of the piston-cylinder unit anddrivable by the crankshaft to compress refrigerant, an additional objectof the invention is achieved in that the refrigerant compressor has alubricant receptacle according to the invention in order to conveylubricant from a lubricant sump arranged in a bottom region of thecompressor housing to the piston-cylinder unit via the crankshaft,wherein the lubricant receptacle is fixedly connected to the crankshaft.

By using a lubricant receptacle according to the invention in ahermetically sealable refrigerant compressor—particularly due to theasymmetric formation of the end region of the lubricant receptacle inrelation to rotations of the projection of the end region about thecenter point between the longitudinal axis of the receiving portion andthe end region—it is possible to ensure a lubrication of all componentsof the refrigerant compressor requiring lubrication that is improved incomparison to conventional, i.e. symmetrical lubricant receptacles,since the lasting closure of the inlet opening by formation of gasbubbles in the region of the lubricant receptacle or the inlet openingcan be avoided and the influence of fluctuations of the lower apex ofthe paraboloid on the overall lubricant conveying system can be reduced.

Due to the continuous lubricant flow from the receiving portion into thecrankshaft and from the crankshaft via exit openings to the componentsof the refrigerant compressor requiring lubrication during operationalusage of the lubricant receptacle, it is necessary to ensure acontinuous resupply of lubricant into the receiving portion of thelubricant receptacle.

In a particularly preferred embodiment of the refrigerant compressoraccording to the invention, it is provided for this purpose that the endregion of the lubricant receptacle protrudes at least in certainportions into the lubricant sump so that the inlet opening is arrangedwithin the lubricant sump in order to enable entry of lubricant from thelubricant sump into the receiving portion of the lubricant receptacle.

In order to favor the formation of the paraboloid shape of the lubricantin the receiving portion, another particularly preferred embodiment ofthe refrigerant compressor according to the invention provides that thelubricant receptacle is fastened by means of the fastening portion to anend portion of the crankshaft remote from the piston cylinder unitand/or to the rotor.

In particular, it can be provided that an internal diameter of thereceiving portion of the lubricant receptacle coincides with a clearinternal diameter of the crankshaft, and that the fastening portion ofthe lubricant receptacle is pressed from the outside onto the endportion of the crankshaft, so that a continuous transition between thereceiving portion of the lubricant receptacle and the crankshaft isensured.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be explained in detail with reference toembodiments. The drawings are for the sake of example and are intendedto present the inventive concept, but not to restrict it, much lessreproduce it exhaustively

Therein:

FIG. 1 shows a lubricant receptacle according to the invention,

FIG. 2 shows the lubricant receptacle from FIG. 1 viewed along thelongitudinal axis thereof,

FIG. 3 shows a refrigerant compressor according to the invention havinga lubricant receptacle according to the invention, and

FIG. 4 shows the lubricant receptacle according to the invention with alubricant paraboloid forming in the lubricant receptacle in an operatingstate of the refrigerant compressor.

MODES FOR EMBODYING THE INVENTION

FIG. 1 shows an embodiment variant of a lubricant receptacle 1 accordingto the invention. The lubricant receptacle 1 is constructed from aplurality of sleeve-like portions, each having constant diameter,wherein the transitions between these portions of constant diameter arecontinuous in the embodiment variant shown, but can also be discrete,i.e. step-shaped for example, without loss of generality.

The lubricant receptacle 1 comprises a fastening portion 16 forfastening the lubricant receptacle 1 to a crankshaft 2 or a rotor 11 ofa lubricant compressor 3 (see FIG. 3), and a receiving portion 4, usedfor receiving lubricant, adjoining the fastening portion 16 and having adiameter that is reduced in comparison to the fastening portion 16.

This receiving portion 4 itself has a cylindrical lateral surface and isclosed off by an end region 5 of the lubricant receptacle 1 at the lowerside, i.e. at a side remote from the fastening portion 16.

The above yields a sleeve-like structure of the lubricant receptacle 1,which is open toward the top and closed off by the end region 5 towardthe bottom, apart from an inlet opening 6 for lubricant. Both thefastening portion 16 and the receiving portion 4 are rotationallysymmetrical relative to rotation about a longitudinal axis 8 of thereceiving portion 4.

In the operating state of the lubricant receptacle 1, in which thelubricant receptacle 1 is arranged coaxially with crankshaft 2 androtationally fixedly connected to the crankshaft 2, the inlet opening 6establishes a fluidic connection between a housing interior of therefrigerant compressor 3 and the receiving portion 4.

FIG. 2 shows the lubricant receptacle 1 from FIG. 1 as a two-dimensionalprojection along the longitudinal axis 8 of receiving portion 4. Inparticular, the arrangement and shape of the inlet opening 6 arranged inthe end region 5 is clearly visible in FIG. 2.

The shape of the inlet opening 6, which is formed as an elongated holein this specific embodiment, has the effect that a projection 18 of theend region 5 along the longitudinal axis 8 is no longer symmetricalunder rotation about an intersection point 19 of the longitudinal axis 8with the end region 5. Only the rotation of the projection 18 about theintersection point 19 by an angle of 360° images the projection 18 ofthe end region 5 back on itself, and therefore the condition forrotational symmetry, according to which two-dimensional objects arerotationally symmetrical if a rotation about a point by every arbitraryangle images the object onto itself, is specifically not fulfilled.

Precisely this asymmetry of the end region 5 of the lubricant receptacle1 caused by the inlet opening 6 has the effect that, in the operatingstate of the lubricant receptacle 1—in which operating state thelubricant receptacle 1 is rotationally fixedly connected to thecrankshaft 2 of the refrigerant compressor 3 and arranged coaxially withthe crankshaft 2 such that at least the end region 5 protrudes inportions into a lubricant sump 7 of the refrigerant compressor 3 (seeFIG. 3)—no gas bubbles interrupting the lubricant flow are formed in theregion of the lubricant receptacle 1, more particularly in the region ofthe inlet opening 6, and a continuous lubricant supply for allcomponents intended to be lubricated in the refrigerant compressor 3 canbe ensured.

FIG. 3 shows an embodiment variant of the refrigerant compressor 3according to the invention comprising, in a compressor housing 9, adrive unit 10, a piston-cylinder unit 13 and a crankshaft 2 connectingthe drive unit 10 to the piston cylinder unit 13, wherein the lubricantreceptacle 1 according to the invention is connected coaxially androtationally fixedly to the crankshaft 2 in such a manner that thelubricant receptacle 1 protrudes at least in portions into the lubricantsump 7 formed in a bottom region 17 of the compressor housing 9.

In the illustrated embodiment variant, the crankshaft 2 is rotationallyfixedly connected to the rotor 11 surrounding a stator 12 of the driveunit 10 for the refrigerant compressor 3 according to the invention, andis set into rotation by the drive unit 10. This rotational movement ofthe crankshaft 2 firstly causes a piston 14 of the piston cylinder unit13 to be moved periodically back and forth between two dead centerpoints of a cylinder 15 in order to draw in refrigerant from the housinginterior, compress it and then discharge it; secondly, the rotatingcrankshaft 2 also sets the lubricant receptacle 1 into a rotationalmotion which has the effect that the lubricant having reached thereceiving portion 4 through the inlet opening 6 assumes the shape of aparaboloid 20.

With an appropriate selection of the production parameters for thelubricant receptacle 1 (in particular the internal diameter of thereceiving portion 4) and of the process parameters for the operatingstate of the refrigerant compressor 3 according to the invention (inparticular the rotational speed of the crankshaft 2), the lubricant inthe receiving portion 4 reaches a level due to the shape of theparaboloid 20 that enables a passage of lubricant from the lubricantreceptacle 1 into the crankshaft 2.

For further conveyance of the lubricant, the crankshaft 2 can beproduced at least in portions as a hollow cylinder, in which caselubricant can escape from the crankshaft 2 via openings in the lateralsurface of the hollow cylinder and reach the components of therefrigerant compressor 3 provided for lubrication; in such a case, themaximum level must reach at least up to a first opening in the lateralsurface. The crankshaft 2 can also be implemented as a solid cylinder,however, and be furnished with an eccentric bore 21, generally runningupward at an incline, by means of which bore 21 the further conveyanceof the lubricant is achieved. In the case of an inclined bore 21, alower maximum level of the lubricant may sometimes be sufficient,because it need merely enable a passage of lubricant into the bore 21and not cover the entire distance up to the first opening. Within theinclined bore 21 of the crankshaft 2, the lubricant is pressed against awall of the bore 21 and thereby conveyed up to the first opening in thelateral surface of the crankshaft 2.

FIG. 4 shows a lubricant receptacle 1 connected to a crankshaft 2 in therefrigerant compressor 3 at different points in time t, t+1, t+2 and t+3of an operating state of the refrigerant compressor 3. In time step t,the paraboloid 20 can be seen without gas bubbles. As soon as theoutgassing effect begins within the lubricant receptacle 1, the shape ofthe paraboloid changes. An apex 22 of the paraboloid 20 drops fartherand farther in the direction of the end region 5 of the lubricantreceptacle 1, as the development of the paraboloid 20 from time t viatime t+1 up to time t+2 shows. Finally a part of the paraboloid—namelythe part containing the gas bubble—can escape the lubricant receptacle 2via the inlet opening 6 as soon as the apex 22 of the paraboloid 20reaches the end region 5. This is ensured in that the inlet opening 6 isarranged surrounding the longitudinal axis 8 in the end region 5. Whilethe gas bubble is leaving the lubricant receptacle 1 through the inletopening 6, it closes the latter off and thereby prevents lubricant fromreaching the lubricant receptacle 1 from the lubricant sump 7. The factthat the inlet opening 6 either has a circular peripheral shape and acenter of the outlet opening is offset from the longitudinal axis 8, orthat the inlet opening 6 has a non-circular peripheral shape viewed inthe direction of the longitudinal axis, ensures however that the gasbubble becomes unstable and tears away from the lubricant receptacle 1or from the inlet opening 6 and again releases it.

LIST OF REFERENCE NUMBERS

-   1 Lubricant receptacle-   2 Crankshaft-   3 Refrigerant compressor-   4 Receiving portion-   5 End region-   6 inlet opening-   7 Lubricant sump-   8 Longitudinal axis-   9 Compressor housing-   10 Drive unit-   11 Rotor-   12 Stator-   13 Piston-cylinder unit-   14 Piston-   15 Cylinder-   16 Fastening portion-   17 Bottom region-   18 Projection of the end region-   19 intersection of longitudinal axis and end region-   20 Paraboloid-   21 Bore of the crankshaft-   22 Apex of the paraboloid

1. A lubricant receptacle for vertical conveyance of lubricant by meansof a crankshaft of a refrigerant compressor, the lubricant receptaclecomprising at least one rotationally symmetrical sleeve-shaped receivingportion for receiving lubricant, wherein the longitudinal axis of thereceiving portion can be arranged coaxially with a longitudinal axis ofthe crankshaft of the refrigerant compressor (3), a fastening portionadjoining the receiving portion in order to fasten the lubricantreceptacle to the crankshaft, and at least one end region adjoining thereceiving portion and closing off the receiving portion apart from aninlet opening, wherein the inlet opening enables the entry of lubricantfrom a lubricant sump of the refrigerant compressor into the receivingportion of the lubricant receptacle, said lubricant receptacleprotruding at least in portions into the lubricant sump, wherein theinlet opening is arranged in the end region surrounding the longitudinalaxis, wherein the inlet opening, as viewed in the direction of thelongitudinal axis, has either a circular peripheral shape and a centerof the inlet opening is offset from the longitudinal axis, or the inletopening has a non-circular peripheral shape as viewed in the directionof the longitudinal axis.
 2. The lubricant receptacle according to claim1, wherein the inlet opening, viewed in the direction of thelongitudinal axis, has the shape of an ellipse.
 3. The lubricantreceptacle according to claim 1, wherein the inlet opening has the shapeof an elongated hole.
 4. The lubricant receptacle according to claim 3,wherein the elongated hole is delimited in a semicircular shape at bothends and the long side of the elongated hole is longer than the radiusof the semicircular delimitations.
 5. The lubricant receptacle accordingto claim 4, wherein the length of the long side of the elongated hole isbetween the value of the radius of the semicircular delimitations andtwice the value thereof.
 6. The lubricant receptacle according to claim1, wherein the size of the inlet opening is between 5 and 30 percent ofthe clear cross-sectional area of the receiving portion.
 7. A systemcomprising a crankshaft of a refrigerant compressor and a lubricantreceptacle according to claim 1, wherein the lubricant receptacle isarranged coaxially with the crankshaft and is rotationally fixedlyconnected to the crankshaft.
 8. A refrigerant compressor having ahermetically sealable compressor housing, an electrical drive unitarranged in a housing interior of the compressor housing and comprisinga rotor and a stator, a crankshaft rotationally fixedly connected to therotor, and a piston-cylinder unit which is arranged in the housinginterior and comprises a piston movably mounted in a cylinder of thepiston-cylinder unit, which piston can be driven by the crankshaft tocompress refrigerant, wherein the refrigerant compressor has a lubricantreceptacle according to claim 1 in order to convey lubricant from alubricant sump formed in a bottom region of the compression housing viathe crankshaft to the piston-cylinder unit, wherein the lubricantreceptacle is rotationally fixedly connected to the crankshaft.
 9. Therefrigerant compressor according to claim 8, wherein the end region ofthe lubricant receptacle protrudes at least in portions into thelubricant sump such that the inlet opening is arranged within thelubricant sump in order to enable entry of lubricant from the lubricantsump into the receiving portion of the lubricant receptacle.
 10. Therefrigerant compressor according to claim 8, wherein the lubricantreceptacle is fastened by means of the fastening portion to an endportion of the crankshaft remote from the piston-cylinder unit and/or tothe rotor.
 11. The lubricant receptacle according to claim 6, whereinthe between 5 and 30 percent of the clear cross-sectional area isbetween 10 and 25 percent.
 12. The lubricant receptacle according toclaim 11, wherein the between 10 and 25 percent is between 15 and 20percent.